Audio systems can include the capability to change one or more parameters of the audio signals to cause a desired effect in the sound perceived by a listener in the listening environment. The effects caused are typically variation of the signal level and/or the equalization of the sound in the listening environment. Audio system designers developing systems for use in noisy environments, such as motor vehicle cabins, airports, restaurants, etc., desire to use the systems in the actual environment while retaining the capacity to tune the system's dynamic parameters, with the aim of developing a system that performs well under different conditions of the listening environment. This effort requires repeated and extensive use of the listening environment under actual use conditions, which can be difficult and expensive.
Some audio systems for listening environments in which noise in the listening environment can change are dynamically adjusted in an attempt to account for the changes in noise. One example of such an environment is the cabin of a motor vehicle. Engine sounds, road noise, and noise from other conditions of the listening environment such as wind noise associated with the state of the vehicle windows (up, partially open or fully open) affect the perception of sounds being played over the audio system. One acoustic compensation system senses the sound in a motor vehicle interior, extracts the noise from the sensed sound, and adjusts the audio signals in a predetermined manner to account for the noise. For example, the reproduction level, dynamic range, and frequency response can be varied based on an analysis of the noise.
It can also be desirable to alter the perception of engine sounds in a vehicle cabin, for example by canceling or enhancing them. Audio systems incorporating acoustic compensation systems can accomplish this by creating audio signals based on the engine harmonics.
Systems that allow virtual evaluation of certain aspects of audio systems are known. For example, virtual listening via headphones can be used for subjective evaluation. Such virtual listening systems can include the addition of pre-recorded noise to the audio output, to mimic the actual environment.